Assemblies incorporating a helical spring and means for causing said spring to act in torsion and in so doing to exert frictional gripping forces on a housing-bore surface, or conversely on a shaft, rod or tube outer surface, are known in the prior art, examples of patents broadly utilizing the idea being Diescher No. 631,956 dated Aug. 29, 1899; Kaman et al. U.S. Pat. No. 2,890,027 dated June 9, 1959; Keden U.S. Pat. No. 3,230,595 dated Jan. 25, 1966; and Norton et al. U.S. Pat. No. 3,517,184 dated June 3, 1970. However, no one of these prior art patents or any other patent known to applicants teaches or suggests the use of conventional retaining ring-in-groove means, the simplicity and effectiveness of which is widely known and utilized in countless other and diverse assemblies, as an artificial shoulder-forming means which functions in concert with a natural shoulder to position a multi-coil helical spring so that it may act like a torsion spring, and which in so doing, generates friction gripping forces effective on a housing-bore surface, or conversely on a shaft or a rod surface or on the outer surface of a tube or tube-end, for example.